Fescue forage is a major nutritional source for cattle in the United States, especially in the Eastern sector. The fungus Acremonium coenophialum that is endemic to fescue and considered a symbiont produces ergopeptide and other alkaloids that are causally related to inferior production and health in cattle via ill-defined mechanisms involving metabolism and/or nutrient intake. As a result, growth rate and milk production are decreased and reproductive problems occur in animals that are fed endophyte-infected fescue. According to the results of a 1990 national survey of twenty-one tall fescue-growing states with twenty-five million acres of tall fescue, the alkaloid toxicity associated with the intake of fungus-infested fescue currently results in an estimated 609 million dollar annual loss to the cattle industry. Elimination of the fungus from rescue is both impractical and undesirable because the alkaloids produced by this fungus afford increased heartiness to plants by increasing drought and pest resistance. An alternative to the elimination of the fungus from fescue grass is to prevent the effects of the toxic-fungal alkaloids with either chemotherapeutic agents or a vaccine for the prophylaxis of this major production-limiting disease in cattle and horses.
The use of chemotherapeutic agents to treat the effects of the toxic-fungal alkaloids requires a continued investment in time and money for those involved in raising cattle and horses on fescue forage. An effective vaccine to toxic-fescue alkaloids has several advantages over the use of chemotherapeutic agents. Vaccines are relatively easy to administer using one or a few injections; vaccines are more economical than the continuous treatments required with chemotherapeutic agents; and vaccines have a smaller potential for residue problems. Thus, there would be significant economic benefit to cattle and horse producers with the availability of a successful vaccine to treat the symptoms of fescue toxicosis.
It is an object of the present invention to provide a method for the treatment of the symptoms of fescue toxicosis in mammals.
It is also an object of the present invention to provide a vaccine for treating the symptoms of rescue toxicosis in mammals.
It is a further object of the present invention to provide a protein-alkaloid conjugate for the preparation of a vaccine for treating the effects of rescue toxicosis.